US launches urgent evacuation for damaged dam

Authorities ordered the evacuation of low-lying areas of Oroville, Yuba and other towns downstream from Oroville Dam on Sunday, citing a "hazardous situation" at the tallest dam in the US. According to US Census data, over 160,000 people live in the area. 

The dam's main spillway was severely damaged by erosion last week, prompting authorities to activate the emergency outlet. On Sunday, Butte County Sheriff's department said that the auxiliary spillway also suffered "severe" damage through its use.  

"Failure of the auxiliary spillway structure will result in an uncontrolled release of flood waters from Lake Oroville," the sheriff's department said on social media, ordering the evacuation and adding "This is NOT A Drill. This is NOT A Drill. This is NOT A Drill."

After advising that the spillway was predicted to fail imminently, Butte County Sheriff Korey Honea said at an evening press conference that erosion was not progressing as rapidly as had been feared and the amount of water flowing over the spillway had dropped quickly. 

Oroville dam itself was "sound" and structurally separate from the auxiliary spillway, a spokesperson for the California Department of Water Resources told a public TV channel in San Francisco. 

The barrier is 770-feet (235 meters) high, making it 14 meters taller than the more famous Hoover Dam. Lake Oroville's water level has risen this winter due to heavy rain and snowfall, which came after years of drought. On Friday, water levels were reported to be around two meters from the top of the wall.

The structure is almost 50 years old and located upstream from the town of Oroville, which has 16,000 residents.

Evacuation centers were set up at a fairground in Chico, 20 miles northwest of Oroville.